/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/GeometryScriptSelectionTypes.h
Convert the current selection to aTArray, optionally converting to ConvertToType. For (Tri|Group)=>Vtx, all triangle vertices (in triangles or PolyGroups) are included. For Vtx=>Tri, all one-ring vertices are included. For Group=>Tri, all Triangles are found via enumerating over mesh. (Tri|Vtx)=>Group, all GroupIDs of all triangles/one-ring triangles are included
[EGeometryScriptIndexType](API\Plugins\GeometryScriptingCore\GeometryScript\EGeometryScriptIndexType) ConvertToMeshIndexArray ( const [UE::Geometry::FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) & Mesh, [TArray](API\Runtime\Core\Containers\TArray)< int32 > & IndexListOut, [EGeometryScriptIndexType](API\Plugins\GeometryScriptingCore\GeometryScript\EGeometryScriptIndexType) ConvertToType ) const